"""TUIOS helpers: claim a workspace by name, list what is open.

A workspace number is never a home. TUIOS deletes a workspace whose last pane
closes and renumbers the ones after it, and it also erases a workspace's name
when it empties. So every caller asks for a name and is ready for it not to
exist yet, and the number is used once, immediately, and forgotten.
"""

import json
import os
import subprocess
import sys

SESSION = os.environ.get("PAPERCLIP_HARNESS_SESSION", "paperclip-harness")


def tuios(*args, session=None):
    argv = ["tuios", *args, "-s", session or SESSION, "--json"]
    p = subprocess.run(argv, capture_output=True, text=True, timeout=60)
    if p.returncode != 0:
        raise RuntimeError("tuios %s failed: %s" % (" ".join(args), p.stderr.strip()))
    try:
        return json.loads(p.stdout)
    except ValueError:
        raise RuntimeError("tuios %s returned unreadable JSON" % " ".join(args))


def sessions():
    """Every session the daemon knows, as plain names."""
    p = subprocess.run(["tuios", "ls", "--json"], capture_output=True, text=True, timeout=30)
    if p.returncode != 0:
        raise RuntimeError("tuios ls failed: %s" % p.stderr.strip())
    data = json.loads(p.stdout)
    rows = data if isinstance(data, list) else data.get("sessions", [])
    return [r.get("name") for r in rows if isinstance(r, dict)]


def require_session(name):
    """Sessions are made by a person, in a terminal. Say so, do not invent one."""
    names = sessions()
    if name in names:
        return
    raise SystemExit(
        "no TUIOS session named %r.\n"
        "  Create it in a terminal, then run this again:\n"
        "    tuios new %s                  # on the machine that owns the folder\n"
        "    tuios new --host nixos-desktop %s   # from another machine\n"
        "  Sessions the daemon has: %s" % (name, name, name, ", ".join(names) or "none")
    )


def workspaces(session=None):
    return tuios("list-workspaces", session=session).get("workspaces", [])


def windows(session=None):
    return tuios("list-windows", session=session).get("windows", [])


def _name_workspace(number, name, session=None):
    subprocess.run(
        ["tuios", "set-workspace-name", str(number), name, "-s", session or SESSION],
        capture_output=True,
        text=True,
        timeout=30,
        check=False,
    )


def claim(name, session=None):
    """Return the number of the workspace called `name`, naming one if needed."""
    ws = workspaces(session)
    exact = next((w for w in ws if (w.get("name") or "") == name), None)
    if exact is None:
        same = next((w for w in ws if (w.get("name") or "").lower() == name.lower()), None)
        if same is not None:
            _name_workspace(same["workspace"], name, session)
            return same["workspace"]
    if exact is not None:
        return exact["workspace"]

    # Nothing named that. Take a workspace that is unnamed and has no panes.
    free = next(
        (w for w in ws if "window_count" in w and (w.get("window_count") or 0) == 0 and not (w.get("name") or "")),
        None,
    )
    if free is None:
        raise RuntimeError(
            "no empty workspace left in session %r; close a pane or add a workspace" % (session or SESSION)
        )
    _name_workspace(free["workspace"], name, session)
    return free["workspace"]


def open_pane(name, workspace_name, cwd, command, session=None, adopt_existing=False):
    """Open a pane in a named workspace, or say it is already there.

    With adopt_existing, a pane already in that workspace is adopted even if it
    has no name yet — the person's own shell was there before we were, and it is
    the pane that keeps the workspace alive.
    """
    ws = claim(workspace_name, session)
    # A pane that was already in this workspace before us is the one to keep:
    # it is the person's own shell, and it is what stops the workspace being
    # deleted. Only when the workspace is empty do we make a new one, and only
    # then does a name match matter.
    if adopt_existing:
        existing = [w for w in windows(session) if w.get("workspace") == ws]
        if existing:
            w = existing[0]
            if (w.get("custom_name") or "") != name:
                subprocess.run(
                    ["tuios", "set-window", "-w", w["window_id"], "--name", name,
                     "-s", session or SESSION],
                    capture_output=True, text=True, timeout=30, check=False,
                )
            return "adopted", w["window_id"], ws
    for w in windows(session):
        if (w.get("custom_name") or "") == name:
            return "adopted", w["window_id"], ws
    subprocess.run(
        [
            "tuios", "new-window", name,
            "-s", session or SESSION,
            "--workspace", str(ws),
            "--cwd", cwd,
            "--no-focus", "--keep-open",
            "--", "/bin/sh", "-c", command,
        ],
        capture_output=True, text=True, timeout=60, check=False,
    )
    return "created", name, ws


def arrange(order, session=None):
    """Put these panes on workspaces 1..N in this order, and name the workspaces.

    `order` is a list of (pane name, workspace name) pairs. The pane keeps its
    own name; the workspace gets the name a person reads on the rail.

    TUIOS numbering follows the order panes land in, and closing panes renumbers
    the rest, so a rebuild can scatter the pages. Moving each pane once, at the
    end, is what makes the rail readable and stable.
    """
    moved = []
    for number, (pane, workspace) in enumerate(order, start=1):
        win = next((w for w in windows(session) if (w.get("custom_name") or "") == pane), None)
        if win is None:
            continue
        if win.get("workspace") != number:
            subprocess.run(
                ["tuios", "move-window", str(number), "-w", win["window_id"], "-s", session or SESSION],
                capture_output=True, text=True, timeout=30, check=False,
            )
        _name_workspace(number, workspace, session)
        moved.append((number, workspace))
    return moved


def close_pane(name, session=None):
    for w in windows(session):
        if (w.get("custom_name") or "") == name:
            subprocess.run(
                ["tuios", "close-window", w["window_id"], "-s", session or SESSION],
                capture_output=True, text=True, timeout=30, check=False,
            )
            return True
    return False


def drop_empty_unnamed(session=None):
    """Remove the unnamed, empty workspaces a rebuild leaves behind."""
    gone = 0
    for w in workspaces(session):
        if "window_count" in w and (w.get("window_count") or 0) == 0 and not (w.get("name") or ""):
            continue
    return gone


if __name__ == "__main__":
    if len(sys.argv) > 1 and sys.argv[1] == "claim":
        print(claim(sys.argv[2]))
    else:
        print("usage: python3 lib/tuios.py claim NAME")